Field
Implementations of the present disclosure generally relate to the fabrication of integrated circuits. More particularly, the implementations described herein provide techniques for deposition of boron-containing amorphous carbon films on a substrate with reduced particle contamination.
Description of the Related Art
One of the primary processes in the fabrication of modern semiconductor devices is the formation of a thin film on a semiconductor substrate by chemical reaction of gases. Such a deposition process is referred to as chemical vapor deposition or CVD. Conventional thermal CVD processes supply reactive gases to the substrate surface where heat-induced chemical reactions take place to produce a desired film. The high temperatures at which some thermal CVD processes operate can damage device structures having metal layers previously formed thereon.
Processes that have been developed to deposit mask materials at relatively low temperatures include plasma-enhanced CVD (PECVD) techniques. Plasma-enhanced CVD techniques promote excitation and/or disassociation of the reactant gases by the application of radio frequency (RF) energy to a reaction zone near the substrate surface, thus creating plasma of highly reactive species. The high reactivity of the released species reduces the energy required for a chemical reaction to take place, and thus lowers the required temperature for such PECVD processes.
The surface upon which a CVD layer is deposited may contain sorbable contaminants such as fluorine deposits from chamber cleaning and dopants from other processes. The presence of fluorine or other sorbable contaminants, for example, boron, may affect the absorption of precursors and slow or inhibit the deposition rate of the CVD layer. Fluorine in the chamber can also form particles when contacted by the reactive gases used to deposit a PECVD layer.
Particle contamination within the chamber is typically controlled by periodically cleaning the chamber using cleaning gases, typically fluorinated compounds, which are excited to inductively or capacitively coupled plasmas. Cleaning gases are selected based on their ability to bind the precursor gases and the deposition material, which has formed on the chamber components, in order to form stable volatile products, which can be exhausted from the chamber, thus cleaning the process environment.
Once the chamber has been sufficiently cleaned of the process gases and the cleaning by-products have been exhausted out of the chamber, a season process is performed to deposit a film onto components of the chamber forming the processing volume to seal remaining contaminants therein and reduce the contamination level during processing. This process is typically carried out by depositing a season film to coat the interior surfaces forming the processing volume of the chamber.
While chamber cleaning and deposition of a season film have been successful in reducing most contaminants in a plasma reactor, sorbable contaminants such as fluorine and boron have still been measured above desired levels. Therefore, there exists a need for methods for further reducing sorbable contaminants within a plasma reactor.